#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n, m;
int a[N];

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> m >> n;
  queue<int> q;
  set<int> st;
  int ans = 0;
  rep(i, 1, n) {
    int x;
    cin >> x;
    if (!st.count(x)) {
      ans++;
      if (q.size() == m) {
        st.erase(q.front());
        q.pop();
      }
      st.insert(x);
      q.push(x);
    }
  }
  cout << ans;
  return 0;
}